1. Field of the Invention
Embodiments of the invention generally relate to a semiconductor processing chamber and, more specifically, a liner assembly used in a semiconductor processing chamber.
2. Description of the Related Art
Semiconductor processing involves a number of different chemical and physical processes whereby minute integrated circuits are created on a substrate. Layers of materials which make up the integrated circuit are created by chemical vapor deposition, physical vapor deposition, epitaxial growth, and the like. Some of the layers of material are patterned using photoresist masks and wet or dry etching techniques. The substrate utilized to form integrated circuits may be silicon, gallium arsenide, indium phosphide, glass, or other appropriate material.
In the manufacture of integrated circuits, plasma processes are often used for deposition or etching of various material layers. Plasma processing offers many advantages over thermal processing. For example, plasma enhanced chemical vapor deposition (PECVD) allows deposition processes to be performed at lower-temperatures and at higher deposition rates than achievable in analogous thermal processes. Thus, PECVD is advantageous for integrated circuit fabrication with stringent thermal budgets, such as for very large scale or ultra-large scale integrated circuit (VLSI or ULSI) device fabrication.
One problem that has been encountered during plasma processing is the non-uniform temperature distribution in the processing chamber during processing. In certain systems, two opposing electrodes are disposed in the processing chamber defining a processing zone in the central region of the processing chamber. The opposing electrodes are utilized to maintain a plasma in the processing zone. The plasma provides ionization energy as well as thermal energy utilized to process a substrate disposed within the chamber. As the plasma and thermal energy is generally concentrated in the center region of the processing chamber, a temperature gradient between the center and side regions, e.g., the sidewall, of the process chamber is generated.
The temperature variation is aggravated in processing systems having adjacent processing systems or other external heat source that heats one region or side of a chamber more than another. For example, in a processing chamber body having two plasma processing regions separated by a shared internal wall, the internal wall is heated from the plasma from both regions while the external walls are heated by only one of the plasmas, thereby creating an unbalanced heat load which results in the exterior walls having a lower temperature relative to the internal wall. The low temperature may cause process gases or precursors to condense on the wall surfaces having the reduced temperature, thereby resulting in particle generation that may lead to contamination of the deposited film.
Particles generation within the chamber may also accumulate in and eventually obstruct the pumping port, thereby requiring an interruption in processing to clear the pumping port. Additionally, particles within the chamber may compromise chamber seals, thereby resulting in thermal energy loss and further aggravating the temperature uniformity of chamber walls.
Therefore, there is a need for an improved method and apparatus that improves temperature uniformity along the boundary of the processing region.